OVA
Description
December leads the terrorist organization Tartarus Lapse and holds the title of the tenth Kaleid Blood. She possesses fair skin, short blonde hair, and a baby face, resembling Avrora Florestina and other Kaleid Bloods. Her distinctive attire includes platform shoes, a letterman jacket, a denim miniskirt, and a half-cap-style helmet with windbreak goggles. Despite the platform shoes, her height remains under 160 centimeters.

As the tenth Kaleid Blood, she functioned as the seal for the tenth familiar, Dabih-Crystallus, a role previously held by the Fourth Progenitor, Kojou Akatsuki. She retained the ability to summon this familiar until its transfer back to Kojou. Her past involves captivity under the Third Progenitor, the Chaos Bride, who released her to witness the end of demon districts, an experience fostering her resentment toward artificial demon sanctuaries.

She orchestrates terrorist attacks on Itogami Island, aiming to isolate and destroy it based on her belief that it serves as an altar for resurrecting Cain, the Father of Demons. Her methods involve deploying feng shui-based magical barriers to paralyze transportation and infrastructure, collaborating with Tartarus Lapse members like Senga Takehito, and targeting high-ranking officials to incite chaos. During these events, she encounters Nagisa Akatsuki, rendering her unconscious to communicate with Avrora's soul residing within Nagisa. December declares their actions as "their war" and urges Avrora to return to slumber.

Her confrontation with Kojou Akatsuki employs psychological manipulation; she triggers his traumatic memories of the "Scorched Banquet," the event where he became the Fourth Progenitor by killing Avrora. This tactic inflicts severe mental distress and temporary incapacitation on Kojou. She later engages Kojou directly, attempting to seal his familiars. Though Kojou gains the upper hand, she exploits his guilt over Avrora's death. After Kojou rejects Tartarus Lapse's methods, December activates the "Roses" magical circle to drain energy from demon bracelets, intending to annihilate the island. In the conflict's climax, she returns the tenth familiar to Kojou, fulfilling her role as its former seal.

December expresses a philosophy linking sustenance and peace, notably stating, "Ice cream grudges run deeper than the ocean" to emphasize grievances over denied treats. Her character arc concludes with the dissolution of Tartarus Lapse and her role in the failed keystone destruction, an outcome which inadvertently validates her warnings about Itogami Island's purpose.